Electric toothbrush

ABSTRACT

An electric toothbrush is provided with a rotary brush which is rotated by a reversible electric motor partly controlled by a reversing switch. A longitudinally extending guard is supported alongside the rotary brush for movement in a plane substantially parallel to the axis of rotation of the brush and between a normal position on one side of the brush and other positions. Movement of the guard away from the normal position operates the reversing switch to change the direction of rotation of the motor and thereby the rotary brush.

United States Patent 1 Koblanski Aug. 20, 1974 ELECTRIC TOOTHBRUSH [76] Inventor: John N. Kohlanski, 9904 NE. 14th St., Bellevue, Wash. 98004 [22] Filed: Jan. 8, 1973 [21] Appl. No.: 322,030

[52] US. Cl. 15/23 [51] Int. Cl A61c 17/00, A46b 13/02 [58] Field of Search 15/23, 24; 310/50 [56] References Cited UN1TED STATES. PATENTS 2,279,982 4/1942 Glynn 15/23 3,161,899 12/1964 Poizat l5/23 Primary Examiner-Edward L. Roberts Attorney, Agent, or Firm-Fetherstonhaugh & Co.

[57 ABSTRACT An electric toothbrush is provided with a rotary brush which is rotated by a reversible electric motor partly controlled by a reversing switch. A longitudinally extending guard is supported alongside the rotary brush for movement in a plane substantially parallel to the axis of rotation of the brush and between a normal position on one side of the brush and other positions. Movement of the guard away from the normal position operates the reversing switch to change the direction of rotation of the motor and thereby the rotary brush.

5 Claims, 8 Drawing Figures 3.829.922 sum ear 2 v PATENTEDmcao I874 ELECTRIC TOOTHBRUSH My invention relates generally to electric toothbrushes and more particularly to a toothbrush having a power driven rotary brush the direction of rotation of which can be reversed as required.

Most electric toothbrushes presently in use have a bristle part which is reciprocated through a short are about the longitudinal axis of the toothbrush. Such a reciprocating movement is quite effective in cleaning some areas of the teeth but the action is not one which is best suited to clean other areas such as one near the gumline and particularly adjacent the cheek. A rotating brush is recognized as being a better cleaner than a reciprocating brush but the former brush has a number of disadvantages which detract from its suitability for use as a toothbrush. For example, a rotary brush when rotated in one direction only has a tendency to drive food particles and the like between the teeth when the brush is rotating towards the gums.

I have overcome the disadvantages to conventional toothbrushes by providing a device with a rotary brush and an adjoining guard which is shiftable from one side or the other of the axis of rotation of the brush whereby the guard can be moved out of the way to allow the brush to reach all corners of the mouth. The movement of the guard is utilized to operate a reversing switch so that the direction of rotation of the brush can be changed as required to brush away from the gums and towards the teeth. It is not necessary to remove the toothbrush from the mouth to change the direction of rotation and the cleaning action is substantially continuous once the toothbrush has been inserted in the mouth. I

In drawings which illustratea preferred embodiment of the invention,

FIG. 1 is a perspective view of a toothbrush in accordance with the present invention,

FIG. 2 is a wiring diagram for a motor of the toothbrush,

FIG. 3 is a plan view of a portion of the toothbrush showing a guard of the device in a normal or resting position,

FIG. 4 is a similar view showing the guard in an alternative operating position,

FIG. 5 is an enlarged vertical section taken on the line 55 of FIG. 1,

FIG. 6 is a horizontal section taken on the line 6-6 of FIG. 5,

FIG. 7 is an enlarged vertical section taken on the line 7--7 of FIG. I, and

FIG. 8 is a schematic view showing the toothbrush being used to clean the teeth.

Referring first to FIG. 1 of the drawings, the numeral 10 indicates generally an electric toothbrush which is provided with a casing 11. Preferably, the handle-like casing 11 is formed of plastic and is shaped so that it can conveniently be gripped in the users hand. The casing 11 is shown as being cylindrical but obviously any other suitable shape may be used. A relatively narrow neck portion 15 projects from one end of the body A suitable direct current electric motor 20 is I jecting end 26 and mounted on this shaft end is a rotary brush 27. A suitable coupling 29 joins opposite end 30 of shaft 25 to the drive shaft 22 and thus the rotary brush 27 can be driven either clockwise or counterclockwise (as viewed in FIG. 1 for example) by the reversible electric motor.

The motor 20 is adapted to be connected to a source of electric power (not shown) by electric circuit mens generally indicated at which includes the usual cord 36 and wall plug 37 illustrated in FIG. 1. As shown best in FIG. 2, the means 35 comprises other elements mounted within the casing 11 along with the reversible motor 20 and these elements may include a suitable transformer 38, a master control switch 39 which may be of a simple on-off type, and a reversing switch 40. The switch 40 is a double pole double throw switch, the operation of which will be described in detail later but it will be obvious from FIG. 2 that when said switch is closed to bridge two adjacent contacts, the motor 20 rotates the brush 27 in one direction and when the switch is closed to bridge the two opposite contacts, the brush is rotated in a reverse direction.

The switch 40 is adapted to be operated by a lever and one end of this lever is enlarged to provide a guard 46 which is positioned alongside the brush 27. Preferably, the guard 46 is semispherical in shape with the flat side thereof opposite the periphery of the brush and spaced a short distance from the tips of the bristles of the brush. The lever 45 may be flexible so that the guard 46 can move towards and away from the brush 27.

Mounting means generally indicated at 50 secure the lever 45 to the casing 11 so that the guard 46 is supported alongside the brush 27 with the lever 45 being shaped substantially to conform to the junction of the hollow body 14 and portion 15 and then extending upwardly to the brush guard 46 at an acute angle to the shaft 25. As shown best in FIGS. 5 and 6, the means 50 comprises a vertically disposed pivot pin 52 which extends through two vertically spaced flanges 53 formed within the casing 11 near the neck portion 15. These flanges 53 provide a horizontal and arcuate slot 54 in the casing. The lever 45 projects through the slot 54 and is supported by the pin 52 so that said lever can be pivoted to dispose the brush guard 46 to one side or the other of the brush 27.

In order that the operating lever 45 may be pivotted in the right direction during a cleaning operation and grally formed on the lever 45 near the guard 46. Band 62 extends transversely of the lever and projects laterally therefrom so as to encircle the neck portion 15. The band 62 may be disposed so as to engage the shaft 25 whereby to halt movement of the guard 46 in two selected positions preferably equally spaced one on either side of the axis of rotation of the brush 27.

The lever 45 is adapted to operate the reversing switch 40 and, for this purpose, inner end 64 of said lever is provided with an arcuate slot 65, see FIG. 6. Switch 40 is secured to the inner surface of the casing 11 so that its movable contact 66 projects through the slot 65. The reversing switch has fixed contacts 67 and 68 as well as other fixed contacts 69 and 70, see FIG.

2, which are curved with the radius of curvature centered about the point of pivot of movable contact 66. Contacts 69 and 70 are spaced only a very short distance from contacts 67 and 68. Thus, when the guard 46 is located to one side of the brush, or in the FIG. 3 position for example, the switch 40 is actuated to interconnect contacts 67 and 68 (FIG. 2) of the switch whereupon the motor 20 is run in one direction. A slight movement of the guard 46 away from the FIG. 3 position will cause the contact 46 to bridge the arcuate contacts 69 and 70 whereby to reverse the motor.

FIGS. 3 and 4 illustrate the two extreme operating positions of the lever 45 and the guard 46 thereon with FIG. I, of course, being a mid-position. For convenience, the FIG. 3 position will be regarded as causing the brush 27 to rotate clockwise as viewed in FIG. 1 and this position will henceforth be referred to as the normal resting position of the lever 45 since said lever is biased to this position by a light spring 74, see FIG. 6. Spring 74 is secured at one end to the lever 45 and is anchored at the opposite end to a part of the casing 11. Thus, the reversible motor 20 normally operates to rotate the brush 27 clockwise when viewed from the outer end thereof. As previously explained, when the lever 45 is moved a short distance away from the normal position (FIG. 3), the motor 27 is reversed and the brush is driven counter-clockwise as viewed in FIG. 1.

In operation, the toothbrush is plugged into a wall outlet and toothpaste is applied to the brush 27 which is then placed in the mouth against the teeth where cleaning is to commence. Assuming that the crowns of the teeth are to be cleaned first, the brush 27 can be allowed to rotate in the normal clockwise direction since the direction of rotation is not important at this stage. However, when the brush 27 is to be applied to the teeth near the gumline, it is important that the brush be rotated so as to brush away from the gums and towards the teeth since to do otherwise would tend to drive food particles or the like under the gums which is most undesirable. The toothbrush l0 ensures that the teeth are brushed in the proper direction and how this is accomplished will be understood by reference to FIG. 8. In FIG. 8, it should be noted that the brush 27 and guard 46 which are shown schematically in a number of operating positions are seen as viewed from the outer end of the toothbrush l0 and the mouth parts are as they would appear if viewed from the interior of the mouth.

The position marked A in FIG. 8 shows the brush 27 in use to clean the molars on the upper left side of the jaw near the gumline. Guard 46 is held in the normal resting (FIG. 3) position at this time by the spring 74 and the left cheek applies light downward pressure to the guard as well so that the brush 27 rotates clockwise or away from the gums as required.

When the brush 27 is shifted to clean the other side of the same molars as shown at B, the guard 46 engages the roof of the mouth and is moved downwardly although only through a very short distance. This movement is sufficient to rock the lever 45 whereby to reverse the motor and cause the brush 27 to be driven counterclockwise so that again brushing is done away from the gums. If the toothbrush is held so that the guard 46 does not contact the roof of the mouth as described, it will be found that the band 62 must be pushed into engagement with a mouth part before the bristles of the brush 27 can properly contact the teeth and this will bring about the desired motor-reversing movement of the lever 45 to ensure that the teeth are brushed in the required direction.

The brush 27 may then be used on the inside of the upper right molars or in the position shown at C in FIG. 8. The spring 74 takes over in this position and swings to lever 45 to its normal operating position and the brush 27 again rotates clockwise.

When the upper right molars are cleaned adjacent the cheek, the brush and guard are positioned as shown at D. The right cheek exerts a slight downward pressure on guard 46 at this time to swing the operating lever 45 a sufficient distance away from its normal or springbiased position to cause counter-rotation of the brush 27 which again rotates toward rather than away from the teeth.

The positions E, F, G and H in FIG. 8 show the toothbrush 10 being used to clean the lower molars at which time the operating lever 45 of the reversing switch is moved in the required direction when the guard 46 engages either the cheeks or the tongue. If the guard 46 is not moved sufficiently to pivot the lever 46 and reverse the motor 20 in these positions, the band 62 will serve to bring about the desired lever movement when the brush 27 is applied to the teeth. The brush 27 thus always rotates away from the gums and towards the crowns of the teeth to ensure proper cleaning.

The front incisors and adjacent teeth are cleaned in much the same manner with the brush 27 always being rotated in the right direction, viz., one which will not drive debris between the gums and the teeth. Thus, the user of the present device can perform a thorough cleaning job without removing the brush from his mouth to interupt the brushing operation and with the direction of rotation of the brush being changed by the action of the guard 46 and band 62. In other words, the user need not consider the direction of rotation since this is controlled by the application of the brush to teeth whereby brushing is correctly done at all times and in each location in the mouth.

It should be noted that the construction and operation of the electric toothbrush need not be exactly as described above and that a number of variations or modifications of design are possible within the spirit and scope of the invention. For example, the neck portion 15 need not be as long as is shown in the drawings and the band 62 can be spaced further from the brush 27 if desired. Band 62 need not be oval-shaped as described since a transversely extending bar or the like on the lever 45 (as indicated by dotted lines in FIG. 7) will serve as a shift means 60. The invention contemplates a modified toothbrush wherein the band 62 is dispensed with entirely and the switch 40 is operated manually by the person using the brush. Preferably this would be accomplished by the user manipulating the lever 45 with his fingers during brushing to reverse the motor 20 as required.

I claim:

1. An electric toothbrush comprising a casing, a reversible electric motor carried by the casing, electric circuit means adapted to connect the motor to a source of electric power and including a reversing switch, a rotary brush mounted exteriorily of the casing and operatively connected to the motor, an operating lever for the reversing switch, a guard mounted on the lever and disposed alongside the rotary brush, mounting means securing the lever to the casing and allowing said guard to move in a plane substantially parallel to the axis of rotation of the rotary brush, said reversing switch being actuated by the operating lever to reverse the motor when the guard is moved away from a normal resting position to one side of the rotary brush.

2. An electric toothbrush as claimed in claim 1, and including spring means biasing the lever towards the normal resting position.

3. An electric toothbrush as claimed in claim 1, and including shift means on the lever near the guard and comprising a substantially oval-shaped band encircling a portion of the casing to limit movement of the guard in either direction.

4. An electric toothbrush as claimed in claim 1, in which said mounting means comprises a pivotal connection located intermediate the length of the lever to provide said lever with an inner end projecting into the casing, and said inner end being operatively connected to the reversing switch.

5. An electric toothbrush comprising a casing having a neck portion at one end thereof, a reversible, electric motor mounted within the casing, a rotary brush mounted on one end of a shaft joumalled in the neck portion and operatively connected at the opposite end thereof to the motor, electric circuit means adapted to connect the motor to a source of electric power and including a reversing switch, an operating lever for the reversing switch, a guard mounted on the lever and disposed alongside the rotary brush, mounting means securing the lever to the casing whereby the guard is movable in a plane substantially parallel to the axis of rotation of the rotary brush, said reversing switch being actuated by the lever to reverse the motor when the guard is moved away from a normal resting position to one side of the rotary brush, spring means biasing the lever towards the normal resting position, and shift means for moving the lever in some positions in the mouth, said shift means comprising a transversely ex-,

tending band mounted on the lever and encircling the neck portion to limit movement of the guard in either direction. 

1. An electric toothbrush comprising a casing, a reversible electric motor carried by the casing, electric circuit means adapted to connect the motor to a source of electric power and including a reversing switch, a rotary brush mounted exteriorily of the casing and operatively connected to the motor, an operating lever for the reversing switch, a guard mounted on the lever and disposed alongside the rotary brush, mounting means securing the lever to the casing and allowing said guard to move in a plane substantially parallel to the axis of rotation of the rotary brush, said reversing switch being actuated by the operating lever to reverse the motor when the guard is moved away from a normal resting position to one side of the rotary brush.
 2. An electric toothbrush as claimed in claim 1, and including spring means biasing the lever towards the normal resting position.
 3. An electric toothbrush as claimed in claim 1, and including shift means on the lever near the guard and comprising a substantially oval-shaped band encircling a portion of the casing to limit movement of the guard in either direction.
 4. An electric toothbrush as claimed in claim 1, in which said mounting means comprises a pivotal connection located intermediate the length of the lever to provide said lever with an inner end projecting into the casing, and said inner end being operatively connected to the reversing switch.
 5. An electric toothbrush comprising a casing having a neck portion at one end thereof, a reversible electric motor mounted within the casing, a rotary brush mounted on one end of a shaft journalled in the neck portion and operatively connected at the opposite end thereof to the motor, electric circuit means adapted to connect the motor to a source of electric power and including a reversing switch, an operating lever for the reversing switch, a guard mounted on the lever and disposed alongside the rotary brush, mounting means securing the lever to the casinG whereby the guard is movable in a plane substantially parallel to the axis of rotation of the rotary brush, said reversing switch being actuated by the lever to reverse the motor when the guard is moved away from a normal resting position to one side of the rotary brush, spring means biasing the lever towards the normal resting position, and shift means for moving the lever in some positions in the mouth, said shift means comprising a transversely extending band mounted on the lever and encircling the neck portion to limit movement of the guard in either direction. 